1. Field of the Invention
The present invention relates to a pumping device and, more particularly, to a pumping device for pumping a fluid, including gas and liquid.
2. Description of the Related Art
A pumping device is used to draw a fluid in an external container into a barrel, or to press the fluid in the barrel outward into the external container. The pumping device comprises a pressure relief member mounted on and connected to the barrel to release a portion of the air pressure in the barrel when the air pressure in the barrel exceeds a preset value so as to assure a safe operation of the barrel. However, the air pressure in the barrel cannot be drained outward from the barrel when the pressure relief member fails or malfunctions so that the barrel is easily deformed or broken due to an excessive air pressure in the barrel, thereby causing danger to the user.
A conventional pumping device disclosed in U.S. publication No. 2012/0134852 comprises a ball-shaped blocking body 34 directly received in and abutting a small-diameter section 3533 as shown in FIGS. 5 and 6. Thus, the air is only allowed to bypass to the micro-hole 355 or the exhaustion space 32 and is then introduced outward from the exhaustion portion 313. The ball-shaped blocking body 34 directly abuts the small-diameter section 3533 instead of the outlet end 23. In addition, after the air enters the micro-section 35, the air has to bypass to be drained outward, thereby decreasing the air exhaust effect.
Another conventional pumping device disclosed in U.S. Pat. No. 6,412,669 comprises a movable member 45 having a tapered tip 451 to stop and prevent the air in the air inlet 24 from flowing outward as shown in FIGS. 7 and 8. After the movable member 45 is loosened, the air has to bypass to be introduced outward from the slot 44. However, after the air enters the movable member 45, the air has to bypass to be introduced outward, thereby decreasing the air exhaust effect. In addition, the movable member 45 does not have a hole for draining the air. Further, such a conventional pumping device cannot drain the air successively in a small quantity manner to release the pressure in the barrel gradually, so that the conventional pumping device does not provide a double pressure relief function to release the excessive air pressure in the barrel.
Another conventional pumping device disclosed in U.S. Pat. No. 3,494,514 only comprises a check valve structure and does not have a pressure barrel with a drawing or sucking function. In addition, such a conventional pumping device does not have an air draining function.